Process of eliminating and recovering acids or metallic salts.



H. E. TIFFANY. PROCESS OF ELIMINATING AND RECOVERING ACIDS 0R METALLICSALTS.

APPLICATION 'FILED JAN. 5.1916. 1,6,79

Patented May 15, 1917.

State of Delaware,

UNITED STATES PATENT @FFIGEO HAROLD E. TIFFANY, 01 N EWAIRK, DELAWARE, ASSIGNOR TO THECONTINENTAL FIBRE COMPANY, OF NEWARK, DELAWARE, A CORPORATION OF DELAWARE.

Specification of Letters Patent.

llatented Mayra, rem.

Application filed January 5, 1916. Serial No. 70,477.

To all whom it may concern:

Be it known that I, HAROLD E. TIFFANY, a citizen of the United States, residing at Newark, in the county of Newcastle and have invented certain new and useful Improvements in Processes of Eliminating and Recovering Acids or Metallic Salts, of which the following is a. specification.

My invention relates to an improved process of eliminating acids or metallic salts, such as chlorid of zinc, used in the manufacture of certain fibrous materials, and in recovering same.

Among other things, it consists in the application of electrolysis or an electrolytic method to the washing or puring out of fiber or similar material in sheet, tube, or

other form for the elimination of any metallic salt, such as, for instance, zinc chlorid commonly used in the manufacture offiber, or an acid that will gelatinize and harden cellulose in a way similar to zinc chlorid. Fiber or similar material washed or pured out by my improved electrolytic method is more thoroughly cleansed than has hitherto been possible, and in less .timeyand therefore more economically, and, as practically all the solution is recovered, no extra cost is incurred in consequence.

In the accompanying drawings Figures 1, 2 and 3 are views showing a few of many forms of tankscontaining an electrolyte with positive and negative electrodes, and showing the sheets of fiber arranged therein.

The most approved method now in use of making vulcanized fiber is to wind up layers of paper, each layer being saturated with zinc chlorid. My method is not limited to the use of zinc chlorid, but contemplates the use of any metallic salt, or in fact any acid that'might be used for gelatinizlng cellulose. The action of metallic salt or acid used does not harden the cellulose at once, because it is the cellulose in the paper that the acid affects, the theory being that paper must be used containing as much cellulose as possible, as for instance cotton paper, which is then passed through the bath of acid or metallic salt that gelatinizes or softens the cellulose. Continually winding one sheet upon another in this condition sticks the material together, but the cellulose is not 'to first place the sheets of about 25 B. and then transfer it from tank to tank through a zinc diminishing strength, until at last it reaches pure water, and stays there until all possible traces of the zinc chlorid solution originally used are washed or soaked out, and the product is commercially pure and ready to dry andbe finished in the usual manner.

While it would be perfectly possible to place the sheets in pure water at the start, yet it is economical to use the zinc chlorid solution over and over again, and consequently it is customary to provide along series of tanks, pure water being supplied at one end of the series and pumped forward from tank to tank, while the fiber is started at the other end of the series and moved from tank to tank toward the pure water. In other words, the fiber is moved all the time toward fresh water, and the fresher water is pumped from tank to tank as it becomes stronger and stronger with the chlorid of zinc solution, until finally when the solution at the farthest end reaches a strength of about 25 to 30 B. it is pumped into other tanks, where by boiling, the excess water is evaporated and the strength of the zinc chlorid raised to a point where it can be used for the first solution into which the fiber is placed for its original saturation with the zinc chlorid.

The trouble with this process of washing is that it involves a large amount of labor in moving the fiber fromrtank to tank, and above all it is a long, slow process, requiring from three to five weeks to wash or pure out sheets of fiber only one-eighth of an inch in thickness, and correspondingly longer Where the sheets are of greater thickness.

In my present process, I utilize the wellknown method of electrolysis or electrolytic action, which, briefly described, comprises the action of a direct current of electricity upon an electrolyte made of any solution containing an acid and a metal, or a purely chlorid solution of acid solution, or in fact any solution that will carry an electric current. It is well known that the application of a direct electric current to any of these solutions results in its being separated into its component parts. As for instance, in a tank of water that is pure, or nearly so, the fiber is placed on being taken from the making machine, in which condition it is saturated with the zinc chlorid solution, this zinc chlorid solution becoming readily absorbed into the water and resulting quickly in changing the water from ordinary pure water to a weak solution of zinc chlorid, thereby making it conductive to direct current.

t is perfectly obvious that various elements might be used in the way of electrodes. As shown in the drawings, on one side of the tank 1, into which these sheets of fiber are placed, zinc or other suitable metal which is the negative electrode is placed, and on the other side a sheet or bolt of lead 3 might be employed, as shown in Fig. 1; or, of course, carbon or any other material could be used to form the positive electrode. To each electrode is attached a wire 4 and 5 respectively, connected to the source of direct current, and the current is then turned on, and at once electrolysis or electrolytic action takes place. This causes the zinc chlorid to separate from the fiber and into its component parts, the zinc de-' positing itself upon the negative electrode 2 as metallic zinc and the muriatic acid collecting around the positive electrode and in solution with the water.

By this method of washing or puring out, I have found by actual test that a sheet of fiber one-eighth of an inch in thickness may be entirely cleansed in about twelve hours, so that the fiber thus treated will become a perfect insulator instead of a conductor of electricity, which it would be if any considerable vestige of the zinc or metallic salts remained in its composition.

As an alternative, if desired, each sheet of fiber may be connected to the positive and negative electrode by making the bottom. of the tank one electrode, as shown in Fig. 8, and connecting the sheets together mechanically in some way as illustrated. In fact, any arrangement of electrodes and connection thereto may be used that is found most convenient to the particular situation of the tank, or the size and shape of the sheet of fiber to be pured out. The same thing applies to tubular or other shapes that are "made of fiber. In fact, the fiber sheets when saturated with the zinc chlorid or other metallic salts may form the positive electrodes themselves, and remain so' until the last vestige of zinc chlorid is decomposed and eliminated therefrom.

After I pure out a tank of fiber by my improved process, and the fiber is removed,

there is left in the tank an acid solution, the metallic zinc being separated and deposited in the bottom. I therefore pump the acid solution 05, and concentrate it by evaporation in the presence of the metallic zinc, the two again go into solution, and form zinc-chlorid, which is available for use again in the preliminary stages of manufacture. The zinc chlorid is thus reclaimed as in the old method.

As shown in Fig. 3, the negative elec trode might be in the bottom in the form of a slotted or perforated or grated plate, or an ordinary zinc plate might be placed on the bottom.

Any acid remaining on the surface of the fiber at the conclusion of the process may be readily rinsed OK.

It may not be necessary to connect each fiber sheet mechanically. 1

5 The voltage and amperage may be varied to suit conditions, and also the thickness and number of sheets in the tank, as previously suggested, andthe temperature of the solution; but the higher the voltage, the quicker the action, although if too high, overheating solution, and the necessity of removing it from the finished product.

I claim:

1. The improved method of washing and puring out fiber or similar substance con taining metallic salts or acid, which consists in subjecting the material to electrolytic action.

2. The herein-described method or process of eliminating the metallic salts or acids used in the hardening of fiber, which consists in subjecting the material to electrolvsis. 3. The herein-described method or process ofeliminating the metallic salts or acids used in the hardening of fiber, which consists in subjecting the material to electrolytic action by placing the fiber saturated with thehardening material in an electro lyte and passing a current through it.

4. The herein-described method or process of eliminating the metallic salts or acids used in the hardening of fiber, which consists in subjecting the material to electrolytic action by placing the fiber saturated with the hardening material inan electro- 13o lyte; passing a current through it, and employing the fiber thus saturated as one of the electrodes.

5. The herein-described method or process of eliminating metallic salts or acids used in the treatment of certain fibrous materials and in recovering same, which consists in submerging the fibrous materials in a bath of acid or metallic salts, 'Whichgelatinizes or softens the cellulose therein, then sub- 10 jecting the material under treatment to electrolytic action, whereby to remove and recover the acid or metallic salts, and finally drying the fibrous material treated, which then results in the hardening of the latter.

In testimony whereof I aifix my signature.

, HAROLD E. TIFFANY. 

